The proposed project is aimed at the development and implementation of a highly sensitive colorimetric detection technology for use in rapid medical diagnostic tests, and its application to a peptide-based Lyme disease rapid test as a first example. At the core of the new technology is a novel multi-color chromogenic substrate system for the widely used enzyme label horseradish peroxidase utilizing immobilized forms of color-generation reagents. This technology opens new opportunities for the application of enzyme -linked immunoassays to development of highly sensitive rapid diagnostic tests. The new detection technology will provide a level of sensitivity which is currently unattainable with conventional technologies, but preserving the simplicity, low cost, manufacturability and stability of conventional POC tests. Implementation of the new technology in POC tests will make it possible to develop rapid tests with very short assay time but with analytical sensitivity exceeding that of tests utilizing conventional colorimetric labels, such as colloidal gold or dyed latex particles, as well as microplate ELISA's. Moreover, the sensitivity is expected to compare favorably with the sensitivities of new sophisticated instrument-dependant technologies currently in development for rapid tests. The technology will be applicable to all major formats of current rapid diagnostic, lateral flow, flow through or dip-strip as well as bead filtration assays. The new stable substrate system with its unique multiplexing capabilities will produce bright, high-contrast, colored zones on diagnostic membranes ideally suited for either visual reading or densitometry. To validate applicability of the new detection technology to in vitro diagnostic tests, a new serological lateral flow test for Lyme disease will be developed. At present, there is no point-of-care test for Lyme disease on the market with clinically useful sensitivity and specificity. The new rapid test will utilize two peptide antigens, the C6 peptide of VLsE and the C10 peptide of OspC, and will provide a significant improvement in the diagnostic sensitivity for early phases of the disease over current methods including microplate ELISA's. Turnaround time for the rapid test will be 3-5 minutes, and whole blood as sample type will allow point-of-care use. Performance characteristics of the new rapid test will be evaluated using well-characterized serum samples from Lyme patients with culture-confirmed or physician documented early stage Lyme disease, and on control populations. PUBLIC HEALTH RELEVANCE: This project is aimed at development of a new colorimetric detection technology suitable for point-of-care diagnostic tests, which offers significantly greater sensitivity than current methods. This technology will provide a rapid turnaround, cost-effective solution for point-of-care testing using multicolor visual labels. As a first application, a rapid test for Lyme disease will be developed based on peptide antigens, which will be the first to enable accurate point-of-care serodiagnosis for early Lyme disease.